Radio system



Feb. 25, 1930. s s I 1,748,726

RADIO SYSTEM Filed Janf 25, 1926 Fig.2 I

F T- I T INVENTOR MENDEL O SNOS TORNEY Pat ented Feb. 25, 193.0

PATENT oFFIcE MEnnnL' 'osNos, or BERLI QGERMANY; Ass'ren-eii'ro GESELLSGHAFT rim imnHTLosE IELEGRAPHIEMQB. 151. or ,iagennrmenn rnn r, A oonronn rron or G R ANY" *RADIO SYSTEM Application filed J'anuarygm l flfl, Serial No. 83,452, and in GermanyMarch 12, 1925.

The present invention relates to telephony arrangements of the, kind whereln: an' audlo transformer primary is fed from a -m1crophone or an amplifier unit and is based upon the" idea that-the audio transformer is liable to constitute a source of harmful influences tending to impair faithful reproduction of the timbre. Such distortions of the timbre are ascribable or traceable'to the iron saturation of the transformer by the idle currentv of the microphone orof the amplifier.

According to this invention, this inconven- I ience is obviated by supplyingithe secondary of the transformer with a direct current whichwholly or partly neutralizes the saturation produced in they primary by the idle current. I

' A number of embodiments of the idea underlying the inventionare diagrammatically I point a of condensers '0. joiningitsftwo ends shown in the drawing, in which Fig. 1 shows a diagrammatic sketch of one embodiment of this invention. 7 I Fig. 2 shows a slightly different modified form. r T 7 I Fig. 3 shows a variation of Fig. 2. Fig.3 showsstill another variation.

- Fig. 3? shows another variation.

In Fig. 1 is shown the'well known teleph ony arrangement for, high frequency installationsf (disclosedin German Patent No.

300171), vWherein a telephony iron-cored choke coil (magnetic modulator), provided with a winding w for high frequencypower current and windings g and g for superposed direct current, or microphone (teleph-r ony) current, receivesthe latter from a speech or audio transformer 393. whose priflmary is excited by a microphone. Z2 is a battery furnishing both the idle current of for providing adjustment of the two cur-- rents independently of one another. I Conthe microphone as well as the idle current of winding 9 The resistances r and r serve densers 0 are the shorting condensers serving tochoke off currents of higher frequencies. The primary winding 19 of the 'audlo transformer carries both the speech current i of themicrophone aswell asits' idle (closedcircuit) current Now, in conformity with the inventionthe saturation caused by the said-idle current is neutralized by connecting a-,.d1rect.current source b with the secondary of the'audio transformer, a variable resistance rand protective. choker (Z being inserted,

in the leads} By suitably adjusting there- 'slstance r, it is possible to substantiallyneutrali ze the idle current of the microphone by "-the'd-irect current furnished by 6 from an, amplifier arrangement a subject to microphonemodulation byitelephone t. The

modulation choker T ma'y here consist, for 1 Y instance, of a conductor provided with an iron coat or cover. {Its middle point a serves as 1one.of;' the current-supply terminals for 1 the thigh frequencyalternating current to be controlled or modulated,while-the middle ]c -]c ;{constitu tes the other terminal. The

superposed directcur'rent (idle current) is supplied at the terminals k fromlthe bat.- .tery bthrough resistance T and choke coils d; in parallel relationship thereto is provided the secondary winding 8 of the audio 7 transformer. By the-aid of a. resistance r' connected, for 'mstance,, 1n parallel wlth con denser c 1fi1S'p0SS1lOle-tO ad ust "1nthe sec ondary winding ,sjofthe audio transformer the requisite direct current or ampere, turns furnished bythe battery-6' in order to -.neu

tralize thesaturation caused by the idle current. v. If in this arrangement it is preferredlto place thewinding s of the audio transformer :notin parallel, but in series with thedirect current'source, then," for the purpose of adjustment of thelnecessary direct current or ampere turns it is necessary to disposea regulating circuit'drf' (Fig. 3) or one regu lating circuitin each case, either in parallel with the telephony choker or with the windings (Fig. 3 ),or withr elation to .both'of these QFigQ 3 I It is obvious that theprincipleabovede- I. scribed may be applied to balance out saturation caused by idle currents either in'the I primaryor secondary of any transformer.

Having thus described my invention, what I claim is 1. In a radio system, a transformer consisting of a primary, a secondary and a core, a source of input current to the primary of said transformer and means connected tothe secondary of said transformer adapted to substantially neutralize the saturation of said transformer produced by the input current. V 2 In a radio system, a transformer consisting of a primary, a secondary and a core, a source of input current to the primary of said transformer and means connected to the secondary of'said transformer adapted to substantially neutralize the saturation of said transformer produced by the input current, said latter means consisting of a source of direct current fed to said secondary.

'3. In a radio system, a trans-former consisting of a primary,- a secondary and acore, a source of input current to the primary of said transformer and means connected to the secondary of said transformer adapted to substantially neutralize the saturation of said transformer produced by the input current, said latter means consisting of a source of direct current fed to said secondary, said input current and the said direct current sources bein 'connected in parallel.

L In a radio system, a transformer consisting of a primary, a secondary and a core, a source 0f input current to the primary of said transformer and means connected to the by means of a direct current fed to the secondary of the speech: transformer.

6.v In a transformer having a primary winding, a secondary winding, and a magnetic core, modulating means in circuit with the primary coil having'an idle current flowing therein, means. comprising a circuit having a choke coil and a direct current source in parallel with thesaid secondary winding whereby magnetization of the core due to the said idle current of the rimar windin t is partially neutralized. V

7 In a transformer having a primary winding, a secondary winding, and a magnetic core, a Variable resistance in series with said secondary winding and a condenser in parallel with said resistance, modulating means in circuit with said primary coil having an idle current'fiowing therein, means comprising a direct current source in said secondary circuit whereby magnetization due to said idle currentin said primary winding s is at least partially neutralized.

8 In a transformer having a primary winding, a secondary winding, and a magnetic core, modulating means having an idle current flowing therein, a direct, current source in series with said secondary winding, and means comprising a Variable resistance in series with a telephone choke coil, in par- 'allel with said secondary winding for at least partially neutralizing the magnetization due to the idle current flowing through said primary winding circuit, 1

a MENDEL 'OSNOS.

Till!) 

